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Next item in the popup window is the hydrograph, which graphically summarises the climatological, antecedent and forecast conditions (see Figure 2 and Figure 3).
Figure 2. Example snapshot of the reporting point pop-up window product (for a seasonal forecast).
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Finally, the last part of the reporting point popup window is the probability evolution table. This table shows all the 7 anomaly categories (extreme dry to extreme wet as left to right) and the related probabilities for all the forecast lead time periods and from all the previous forecast runs that verify during the most recent forecast horizon. For the sub-seasonal, this means 5 or 6 calendar weekly forecast lead time periods, depending on which day of the week the run date is, and thus how many calendar weeks the 45-day lead time in the forecast can cover) , and 7 calendar monthly periods for the seasonal. For the seasonal forecasts, there is always 7 rows with the most recent 7 seasonal forecast probabilities (as Figure 2 shows). While for the sub-seasonal, including all the daily (00 UTC) forecast runs verifying in the forecast horizon, there can be 41 to 46 rows. Always as many, as many forecast forecasts can verify in the forecast horizon of the actual real time forecast, and it again depends on which day of the week the run date is. The bottom right corner of the probability evolution table is empty, as those lead times are not available from the earlier forecast runs.
The cells in the table are not coloured, with one exception, which is the dominant of the 7 anomaly categories. That cell's number is bold and the cell is coloured by the same colour that the river pixel has on the river network summary map. As described in Placeholder CEMS-flood sub-seasonal and seasonal forecast anomaly and uncertainty computation methodology, the dominant category is determined by the rank-mean (the mean of the ensemble members' ranks in the climatological percentile distribution). This is why the The coloured cell's number tend to be is not always the highest, like in many forecasts in the example in Figure 2' probability table. For example, although the forecast for August show a gradual progression from near normal (grey colour), which is the original 'Bit low' of the 7 categories , and high uncertainty (lightest grey colour of the three); to 'Extreme low' category with low uncertainty (darkest red colour). Moreover, the number of the coloured cells is also on the increase generally, as we go towards the shorter lead times. Until the June forecast, the colours are the lightest of the three versions, highlighting high uncertainty (light orange in the June forecast), while in the July forecast the uncertainty drops to medium level (medium dark orange) and finally in the August forecast we arrive to the low uncertainty 'Extreme low' situation. At the same time, for all of these forecasts the more likely of the 7 categories are constantly the 'Extreme low' one category, with the probability values gradually increasing until it reaches 100%, so from 2X to 100% in the August forecast (all of the 51 ensemble members are being in the 'Extreme low' category). The reason why the earlier forecasts shift towards the normal conditions in the mean sense is the larger uncertainty with most or all of the categories having some ensemble members.
Basin summary map
The basin summary map is the equivalent of the river network summary map on a larger basin scale. The basins are predefined, as described in
At the predefined reporting point locations (either fixed or basin-representative) further detailed information is provided about the evolution of the forecast signal.
The river network summary map layer shows the combined forecast anomaly and uncertainty signal in a simplified way for each forecast lead time (Figure 1). The lead time is weekly (always Monday to Sunday, with the weekly average river discharge) in the sub-seasonal and monthly (always calendar month, with the monthly average river discharge).
The forecasts can be advanced (or even animated if needed) with the lead time controller (see Figure 1a bottom left corner) and the users can check the individual signal for each lead time, which currently is 5 or 6 weeks for the sub-seasonal (depending on which day of the week the run date is) and always 7 months for the seasonal.
The forecast signal is shown by colouring of all river pixels above a certain minimum catchment area (currently 50 km2 in EFAS and 250 km2 in GloFAS). Each of these river pixels are coloured by the dominant anomaly category and by the uncertainty category.
There are 7 anomaly categories and three uncertainty categories defined based on the extremity level of the ensemble forecast members in the 99-value percentile climatological distribution. The details of the computation methodology is described here: Placeholder CEMS-flood sub-seasonal and seasonal forecast anomaly and uncertainty computation methodology.
On the river network summary map, however, only 5 anomaly categories are displayed, after combining the middle three into one larger 'Near normal' category, which allow the users to the less extreme low anomalies is the larger uncertainty, focus visually on the larger anomalies. Each of these categories are divided into three sub-categories by the uncertainty, as low, middle and high uncertainty, in total making it into 15 forecast signal categories. The inset figure in both Figure 1a and 1b shows the 15 categories and the corresponding colours on the maps.
Figure 1a highlights some river sections with the explanation of the assigned colours and the corresponding anomaly and uncertainty levels. Each of the 5 anomaly categories have a distinct colour, where the 3 uncertainty categories is indicated by lighter colours as the uncertainty increases.
The river network summary map also contains the reporting points, which are labelled as example in Figure 1b. These are river locations, where detailed information is provided about the evolution of the forecast signal over the forecast horizon. There reporting points are either fixed points, which are also used in the medium-range flood products and the basin-representative points, which are selected locations, on a one point per basin basis. Further details about the basins and the representative points are available here: Placeholder CEMS-flood sub-seasonal and seasonal basins and representative stations.